尝试部署到 heroku 时出错（按照 ror 教程）PG::Error: ERROR: column "password_digest" of relationship "users" already exists

Question

所以我关注http://www.railstutorial.org/book，并且 evrything 在本地运行良好（运行 sqlight3）。

我尝试时收到以下错误

heroku 运行 rake db:migrate

这是错误消息的样子

运行 rake db:migrate 连接到终端... up, run.4049 迁移到 AddPasswordDigestToUsers (20140817014655) == 20140817014655 AddPasswordDigestToUsers：迁移 ========================= -- add_column(:users, :password_digest, :string) PG::Error: ERROR: 关系“users”的列“password_digest”已经存在：ALTER 表“用户”添加列“密码摘要”字符变化（255）耙 中止！ StandardError: 发生错误，这个和以后的一切 迁移已取消：

PG::Error: ERROR: 关系“users”的列“password_digest” 已经存在：ALTER TABLE "users" ADD COLUMN "password_digest" 特点 变化（255）/app/vendor/bundle/ruby/2.0.0/gems/activerecord-4.0.8/lib/active_record/connection_adapters/postgresql/database_statements.rb:128:in exec' /app/vendor/bundle/ruby/2.0.0/gems/activerecord-4.0.8/lib/active_record/connection_adapters/postgresql/database_statements.rb:128:in block 正在执行' /app/vendor/bundle/ruby/2.0.0/gems/activerecord-4.0.8/lib/active_record/connection_adapters/abstract_adapter.rb:442:in block in log' /app/vendor/bundle/ruby/2.0.0/gems/activesupport-4.0.8/lib/active_support/notifications/instrumenter.rb:20:in instrument' /app/vendor/bundle/ruby/2.0.0/gems/activerecord-4.0.8/lib/active_record/connection_adapters/abstract_adapter.rb:437:in log' /app/vendor/bundle/ruby/2.0.0/gems/activerecord-4.0.8/lib/active_record/connection_adapters/postgresql/database_statements.rb:127:in execute' /app/vendor/bundle/ruby/2.0.0/gems/activerecord-4.0.8/lib/active_record/connection_adapters/abstract/schema_statements.rb:360:in add_column' /app/vendor/bundle/ruby/2.0.0/gems/activerecord-4.0.8/lib/active_record/connection_adapters/postgresql/schema_statements.rb:395:in add_column' /app/vendor/bundle/ruby/2.0.0/gems/activerecord-4.0.8/lib/active_record/migration.rb:629:in block in method_missing' /app/vendor/bundle/ruby/2.0.0/gems/activerecord-4.0.8/lib/active_record/migration.rb:601:in block in say_with_time' /app/vendor/bundle/ruby/2.0.0/gems/activerecord-4.0.8/lib/active_record/migration.rb:601:in say_with_time' /app/vendor/bundle/ruby/2.0.0/gems/activerecord-4.0.8/lib/active_record/migration.rb:621:in method_missing' /app/db/migrate/20140817014655_add_password_digest_to_users.rb:3:in change' /app/vendor/bundle/ruby/2.0.0/gems/activerecord-4.0.8/lib/active_record/migration.rb:575:in exec_migration' /app/vendor/bundle/ruby/2.0.0/gems/activerecord-4.0.8/lib/active_record/migration.rb:559:in block (2 levels) in migrate' /app/vendor/bundle/ruby/2.0.0/gems/activerecord-4.0.8/lib/active_record/migration.rb:558:in block in 迁移' /app/vendor/bundle/ruby/2.0.0/gems/activerecord-4.0.8/lib/active_record/connection_adapters/abstract/connection_pool.rb:294:in with_connection' /app/vendor/bundle/ruby/2.0.0/gems/activerecord-4.0.8/lib/active_record/migration.rb:557:in migrate' /app/vendor/bundle/ruby/2.0.0/gems/activerecord-4.0.8/lib/active_record/migration.rb:713:in migrate' /app/vendor/bundle/ruby/2.0.0/gems/activerecord-4.0.8/lib/active_record/migration.rb:963:in block 在 execute_migration_in_transaction' /app/vendor/bundle/ruby/2.0.0/gems/activerecord-4.0.8/lib/active_record/migration.rb:1009:in block in ddl_transaction' /app/vendor/bundle/ruby/2.0.0/gems/activerecord-4.0.8/lib/active_record/connection_adapters/abstract/database_statements.rb:203:in 交易中的区块' /app/vendor/bundle/ruby/2.0.0/gems/activerecord-4.0.8/lib/active_record/connection_adapters/abstract/database_statements.rb:211:in within_new_transaction' /app/vendor/bundle/ruby/2.0.0/gems/activerecord-4.0.8/lib/active_record/connection_adapters/abstract/database_statements.rb:203:in transaction' /app/vendor/bundle/ruby/2.0.0/gems/activerecord-4.0.8/lib/active_record/transactions.rb:209:in transaction' /app/vendor/bundle/ruby/2.0.0/gems/activerecord-4.0.8/lib/active_record/migration.rb:1009:in ddl_transaction' /app/vendor/bundle/ruby/2.0.0/gems/activerecord-4.0.8/lib/active_record/migration.rb:962:in execute_migration_in_transaction' /app/vendor/bundle/ruby/2.0.0/gems/activerecord-4.0.8/lib/active_record/migration.rb:924:in block in 迁移' /app/vendor/bundle/ruby/2.0.0/gems/activerecord-4.0.8/lib/active_record/migration.rb:920:in each' /app/vendor/bundle/ruby/2.0.0/gems/activerecord-4.0.8/lib/active_record/migration.rb:920:in migrate' /app/vendor/bundle/ruby/2.0.0/gems/activerecord-4.0.8/lib/active_record/migration.rb:768:in up' /app/vendor/bundle/ruby/2.0.0/gems/activerecord-4.0.8/lib/active_record/migration.rb:746:in migrate' /app/vendor/bundle/ruby/2.0.0/gems/activerecord-4.0.8/lib/active_record/railties/databases.rake:42:in '任务中的`block（2个级别）：TOP => db：migrate（请参阅 通过使用 --trace 运行任务来完整跟踪）

我已经尝试过 heroku pg:reset DATABASE_URL 然后重试。 还尝试将 /spec、/lib、/script、/features、/cucumber.yml 添加到 .slugignore

这是我的架构的样子：

ActiveRecord::Schema.define(version: 20140818041701) do

  create_table "users", force: true do |t|
    t.string   "name"
    t.string   "email"
    t.datetime "created_at"
    t.datetime "updated_at"
    t.string   "password_digest"
    t.string   "remember_token"
    t.boolean  "admin",           default: false
  end

  add_index "users", ["email"], name: "index_users_on_email", unique: true
  add_index "users", ["remember_token"], name: "index_users_on_remember_token"

end

这就是我的密码摘要迁移的样子

class AddPasswordDigestToUsers < ActiveRecord::Migration
  def change
    add_column :users, :password_digest, :string
  end
end

Answer 1

您的表中已经有 password_digest 列，并且通过迁移 AddPasswordDigestToUsers 您正在尝试创建另一个列，这就是它产生问题的原因。删除迁移AddPasswordDigestToUsers 并尝试再次运行rake db:migrate。在这种情况下，Sqlite3 不会产生任何错误。如果你在迁移中写intege而不是integer，如果你使用sqlite，它不会产生任何错误。

Answer 2

如果您只是删除密码摘要迁移文件，它将解决部署到 heroku 的短期问题，但协作者将无法在本地下拉并设置他们的数据库。他们会遇到问题，并且可能会创建另一个迁移文件，从而产生同样的问题。

我不确定最好的解决方案，但到目前为止这似乎对我有用：

class AddPasswordDigestToUsers < ActiveRecord::Migration
  def change
    if Rails.env == "production"
    else
      add_column :users, :password_digest, :string   
    end
  end
end